Power loader



Dec. 13, 1966 E. B. WAGNER POWER LOADER Filed June 1, 1965 INVENTOR EDDIE B. WAGNER United States Patent Ofiice 3,291,330 POWER LUADER Eddie B. Wagner, Portland, reg., assignor to Wagner Manufacturing, Inc., Portland, 0reg., a corporation of Oregon Filed June 1, 1965, Ser. No. 460,049 6 Claims. (Cl. 214-775) This invention relates to :a power loader and has particular reference to an improved linkage for levelling an'd tilting a bucket on the boom of a loader.

A power loader is a vehicle having -a bucket on the end of a forwardly extending boom. The bucket is used as a scoop by tilting it forward and lowering the boom while driving the vehicle forward to scoop material into the bucket. For carrying the load, the boom is raised slightly so that the bucket will clear the ground and the bucket is turned upright on the boom to contain the load. It may be desired to dump the bucket by tilting it forward from either a lower or a raised position.

A problem arises in providing a linkage which will tip the bucket far enough forward to dump its load when the boom is raised as in loading a truck, particularly when a simple form of linkage is employed, mounted directly over the boom. Prior linkages arranged to dump a bucket in a high boom position have been excessively complicated and expensive.

Objects of the invention are, therefore, to provide a simple and improved bucket linkage for a power loader, to provide a linkage on the upper side of a boom which will dump the bucket in elevated position of the boom and to provide an articulated linkage for the purpose described which will also operate under thrust conditions when the bucket and boom are in scooping position.

The objects of the invention are accomplished by a bucket linkage having a joint which will break in one direction to pivot the bucket forward as far as necessary to dump the bucket when the boom is raised and the linkage is under tension. The joint embodies a novel over-center, self-locking geometry which rigidities the linkage so that the joint will not break when the linkage is under compression in scooping position. The provision of such :a joint permits a linkage of relatively simple and economical form of construction to be placed directly above the boom so that the linkage will automatically level the bucket as the boom is being raised and lowered.

The invention will be better understood and the foregoing and additional objects and advantages will become apparent from the following description of the preferred embodiment illustrated in the accompanying drawing. Various changes may be made, however, in the details of construction and arrangement of parts and 'all such modifications within the scope of the appended claims are included in the invention.

In the drawing:

FIGURE 1 is a side elevation view of a power loader embodying the principles of the invention, the bucket and boom being shown in scooping position in full lines and in elevated dumping position in broken lines;

FIGURE 2 is a fragmentary perspective view showing the present linkage and bucket on the end of the boom;

FIGURE 3 is an enlarged longitudinal sectional view showing the joint in the linkage; and

FIGURE 4 is a cross sectional view on the line 4-4 of FIGURE 3.

The present boom and bucket linkage may be mounted on various types of loader vehicles. By way of example, the present vehicle comprises front and rear body sections and 11 which are pivotally interconnected by vertical pins 12 for steering. Steering is accomplished in conventional manner by a pair of angul-arly disposed steering cylinders 13 which interconnect the front and rear body fldlfidd Patented Dec. 13, 1966 sections. The front body section is a motor unit having a motor 14 and a pair of driving wheels 15. The numeral 16 designates a side facing operators seat from which an operator may drive the vehicle and. operate the loader. Body section 11 is supported by a pair of wheels 17 which may be non-driving wheels or driving wheels. In the present illustration the wheels 17 are driven by a drive shaft 8 from the transmission of motor 14 and containing suitable universal joints to accommodate articulation of the two body sections in turning.

Body section 11 carries a boom support frame 18 having a pivot 19 for the boom 20. The forward end of boom 20 carries a pivot pin 21 for a bucket 22 having a scooping or scraping edge 23. The bucket is filled by tilting it forward with the boom lowered as shown in full lines in FIGURE 1 and driving the vehicle toward the material to be scooped.

The pivotal position of the bucket on boom 20 is controlled by the novel bucket linkage 25. Linkage 25 comprises, essentially, an arm 26 which is rigid with the rear end of a double acting hydraulic cylinder 27, a piston rod 28 extending out of the forward end of cylinder 27 and a link 30 pivotally connected with the end of the piston rod by a pin 31. The forward end of link 30 is pivotally connected to bucket 22 by a pin 32 on the rear side of the bucket a distance above its boom support-pin 21. The rear end of arm 26 is pivotally connected to a pin 33 on a bracket 34 which is upstanding from the boom support frame 18.

Hydraulic lines 35 and 36 are connected with the opposite ends of cylinder 27 for extending and retracting piston rod 28 under control of a manual valve from a source of pressure supplied by a hydraulic pump operated by motor 14. The boom 20 is raised by a hydraulic cylinder 49 pivotally mounted at its lower end on a pin 4-1 in boom support frame 18. A piston rod 42 in the upper end of the cylinder is pivotally connected with a pin 43 in the boom. The lower end of cylinder 46 is connected by a hydraulic line to a manual valve and source of hydraulic pressure, as mentioned above.

Link 3% has a rear end portion 5t which extends rearwardly from pivot pin 31 to overhang piston rod 28. This rear end portion 50 is of inverted U-shape in cross section having side walls 51 on opposite sides of the piston rod as shown. Thus, the forward end of link 30 may pivot downward on pin 31 but cannot pivot upward. The front end of boom 20 is forked at 53 to receive the pin 21 and bucket 22 is equipped with a pair of apertured ears 54 to receive this pin. Spanning the opposite sides of fork 53 is a sleeve or roller 55 on pin 21 beneath the link 30.

When link 30 is under tension and is not in contact with roller 55, the extended axis of piston rod 28 intersects the axis of pin 32. This straight line relationship of the link and piston rod is shown in FIGURE 3 where it will be seen that there is a small clearance space 59 between the upper side of piston rod 28 and the confronting under surface 60 of the rear end portion 50 of link 30. Under tension conditions this space may be defined as a small clearance angle 61.

When tension is relieved, and especially when compression is applied to link 30, the joint at pin 31 drops by gravity to close the space 59 causing under surface 60 of the link to bear against the upper side of the piston rod. This produces an over center relation of the parts wherein the extended axis of the piston rod passes below the axis of pin 32. In this condition the linkage 25 is effective in compression so that cylinder 27 will hold the scraping edge 23 of the bucket in depressed position for scooping as shown in full lines in FIGURE 1. Linkage 25 then operates as a rigid thrust member.

When the bucket has been filled by scooping, it is erected to carrying position by retraction of piston rod 28 which returns the piston rod and link 30 to tension condition as shown in FIGURE 3. When the boom is raised, the linkage 25 operates as a constant length link to keep the bucket approximately level for automatic levelling. Even if the bucket should tend to overbalance in a rearward direction, the joint at pin 31 cannot break downward by an amount exceeding the slight angle 61 because under compression the weight of the parts would bring surface 60 to bear against the upper side of the piston rod. Thus, the linkage 25 operates as one side of a parallelogram linkage to stabilize the bucket on its supporting pin 21 as the boom moves up or down.

When the bucket is to be dumped with the boom in lower position, the piston rod 28 is merely extended and, during dumping movement as the bucket tends to overbalance in a forward direction, the piston rod and link 30 remain under tension condition as shown in FIG- URE 3.

The primary advantage of the linkage 25 is utilized in dumping the bucket from a high position of the boom as shown in broken lines in FIGURE 1. As the bucket is rotated counterclockwise to dump its contents, the link 30 comes into contact with roller 55 to break the joint at pin 31 upward as shown. In order to obtain sufiicient counterclockwise rotation of the bucket, the pin 32 must rotate around pin 21 farther than piston rod 28 would permit if the piston rod were connected directly to pin 32. The present arrangement provides a dumping angle which will clear the bucket of all of its contents.

Then, when piston rod 28 is retracted to rotate the bucket clockwise, link 30 fulcrums on roller 55 as a lever arm until the link and piston rod again assume a straight line relationship as shown in FIGURE 3. Thus, it is seen that the joint at pin 31 will break upward but will not break downward whereby the linkage 25 is flexible for high boom dumping but becomes rigid to function as a compression or thrust member for scooping.

This simple arrangement of linkage 25 eliminates a number of additional parts which were heretofore necessary to dump a bucket from a high boom position. Although the present boom 20 comprises a single arm, the same arrangement may be carried out in connection with a boom having a pair of arms in side by side arrangement. In such case, there would be a linkage 25 over each arm of the boom as will be readiy understood by persons skilled in the art.

Having now described my invention and in what manner the same may be used, what I claim as new and desire to protect by Letters Patent is:

1. In a power loader, a boom pivotally mounted for vertical movement, a bucket pivotally mounted on said boom, a linkage connected with said bucket for pivoting the bucket to scooping, carrying and dumping positions, a hinged joint in said linkage having pivotal movement in one direction for tilting the bucket to dumping position, and over-center stop means in said joint arranged to prevent pivotal movement in the opposite direction and make said joint rigid for scooping and carrying.

2. In a power loader, a supporting frame, a boom pivotally mounted on said frame for vertical movement, a bucket pivotally mounted at its bottom on a horizontal pin in said boom, a link pivotally connected with the rear side of said bucket, a linkage member having a horizontal pivotal connection with said link, means for moving said linkage member lengthwise to tilt the bucket, and 60 gravity actuated over center stop means in said last pivotal connection arranged to lock said pivotal connection when said link and linkage member are brought into alignment.

3. A supporting frame, a boom pivotally mounted on said frame for vertical movement, a load carrier pivotally mounted on a horizontal axis on said boom, a linkage unit connected between said frame and said carrier and forming with said boom a parallelogram linkage for stabilizing said carrier during vertical movements of the boom, means for changing the length of said unit to tilt said carrier on said horizontal axis, a pivotal joint in said unit intermediate its ends, and over center gravity locking means arranged to rigidity said joint in load carrying positions of said carrier.

4. In a power loader having a scoop bucket pivotally mounted at its bottom on the end of a vertically movable boom, means for controlling the pivotal position of the bucket on said boom comprising a cylinder extending longitudinally above the boom, a piston rod extending from the forward end of said cylinder, a link pivotally connected at its forward end with the rear side of the bucket, a pivotal joint between said link and piston rod arranged to allow said link to pivot downward from alignment with said piston rod to dump the bucket and to prevent said link from pivoting upward from alignment with said piston rod, and over center stop means in said joint operable by gravity when said link and piston rod are in alignment and not under tension to hold said link and piston rod in approximate alignment for applying thrust to said bucket for scooping.

5. In a power loader, a supporting frame, a boom pivotally mounted on said frame for vertical movement, a bucket pivotally mounted at its bottom on a horizontal pin in said boom, a link pivotally connected with the rear side of said bucket and arranged to fulcrum on said pin when the bucket is tilted forward for dumping while the boom is raised, a cylinder and piston rod unit pivotally connected to said frame above said boom, a horizontal pivot connection between said link and piston rod, and an extended end on said link overhanging said piston rod and arranged to lock said link and piston rod by gravity in over center position when said link and piston rod are disposed in alignment without tension.

6. A boom pivotally mounted for vertical movement, a bucket pivotally mounted on said boom, a linkage unit pivotally connected with said bucket, said linkage unit comprising a pair of linkage members, one of said members comprising a cylinder and piston rod for pivoting the bucket on said boom, a horizontal pivot connection between said members arranged to allow said members to pivot in one direction relative to each other, and overcenter stop means in said last pivot connection arranged to prevent said members from pivoting in the opposite direction relative to each other so that said cylinder and piston rod can exert thrust on said bucket.

References Cited by the Examiner UNITED STATES PATENTS 2,491,793 12/ 1949 Andersen 214- 2,653,722 9/1953 Lull 214-140 2,837,229 6/1958 Markel et al 214-140 3,161,987 12/1964 Decker 21414O X 3,197,050 7/1965 Shumaker 214140 References Cited by the Applicant UNITED STATES PATENTS 3,172,553 3/1965 McCanse.

HUGO O. SCHULZ, Primary Examiner, 

1. IN A POWER LOADER, A BOOM PIVOTALLY MOUNTED FOR VERTICAL MOVEMENT, A BUCKET PIVOTALLY MOUNTED ON SAID BOOM, A LINKAGE CONNECTED WITH SAID BUCKET FOR PIVOTING THE BUCKET TO SCOOPING, CARRYING AND DUMPING POSITIOINS, A HINGED JOINT IN SAID LINKAGE HAVING PIVOTAL MOVEMENT IN ONE DIRECTION FOR TILTING THE BUCKET TO DUMPING POSITION, AND OVER-CENTR STOP MEANS IN SAID JOINT ARRANGED TO PREVENT PIVOTAL MOVEMENT IN THE OPPOSITE DIRECTION AND MAKE SAID JOINT RIGID FOR SCOOPING AND CARRYING. 